JP3228666B2 - Sheet position deviation detecting device, image forming device, and sheet processing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet displacement detecting device provided in a sheet processing apparatus such as a copying machine, a printer, a facsimile, a scanner, and the like. Here, the sheet processing apparatus is a general term for an apparatus having a sheet processing unit that performs a predetermined process (for example, forming an image, reading an image, and the like) on sheets fed one by one. are doing.

[0002]

2. Description of the Related Art In image forming apparatuses such as copiers, printers, and facsimile machines, sheets in a duplex mode and a multiplex mode are temporarily stored in an intermediate tray (sheet stacking means) in the main body of the image forming apparatus for re-forming an image. After the sheets are stacked, the sheets are re-fed one by one from the intermediate tray to the image forming section.

In this case, if a sheet re-fed from the intermediate tray is conveyed to the image forming section in a direction orthogonal to the sheet conveying direction, that is, without any positional displacement in the width direction, the sheet is rejected. An image can be formed at a predetermined position. However, if the sheet re-fed from the intermediate tray is conveyed to the image forming unit in a state of being shifted in the width direction, an image is formed at the shifted position.

In order to eliminate such inconveniences, generally, a positional deviation (lateral deviation) in the width direction of the sheet sent from the intermediate tray is detected, and the sheet position in the image forming section is determined based on the detected lateral deviation. Or the image writing position is corrected.

[0005] Usually, the positional deviation of the sheet in the width direction is performed by sheet end detecting means (sensor) which moves in a direction orthogonal to the sheet conveying direction. The sheet edge detecting means detects the sheet edge by moving in the order of the reference position → the standby position (determined according to the width of the sheet) → the detection position → the standby position after the detection. In the conventional case, the standby position after detection is fixed. Therefore, when the sheet edge detecting means detects the sheet edge, the sheet returns to the same position when the sheet width size is the same.

Usually, the standby position after the detection is different from the standby position before the detection, but the standby position after the detection may be the same as the standby position after the detection.

[0007]

However, when the standby position after detection is fixed as in the above-mentioned conventional example,
The following problems occur.

That is, when the standby position after the detection is set close, the moving sheet may interfere with the sheet end detection means that is waiting at the standby position after the detection.
This occurs particularly in the case of a long sheet having a large size in the transport direction. In the case of a short sheet having a small size in the conveying direction, the sheet end does not approach the sheet end detection unit that is waiting at the standby position even if the sheet is skewed, but in the case of a long sheet with the same sheet width size Even if the sheet is skewed at the same angle as the short sheet, the end of the sheet approaches. If the moving sheet interferes with the sheet edge detection unit in the standby state at the standby position after the detection, the sheet may be torn or jammed.

In order to avoid the above-mentioned problem, when the standby position after the detection is set far away, the sheet end detection means after the sheet end detection waits at a position far from the sheet end. Therefore, the long sheet no longer interferes with the sheet edge detecting means, but a sheet of any length takes a long time to be detected once.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and provides a sheet position deviation detecting apparatus which can cause a sheet end detecting means after a sheet end detection to stand by at a minimum distance where the sheet end does not interfere. The purpose is to provide.

[0011]

SUMMARY OF THE INVENTION The present invention provides a standby position, a detection position for detecting a sheet edge, and a detection position for detecting a sheet edge from a reference position in a direction orthogonal to the sheet conveying direction. The present invention relates to a sheet position shift detecting device that detects a position shift in the width direction of a sheet being conveyed by using a sheet end detecting unit that sequentially performs a detection operation to a subsequent standby position.

In order to achieve the above object, the present invention has a standby position changing means for changing a standby position after the detection by the sheet end detecting means in accordance with a size of a detected sheet in a conveying direction. Features.

The standby position changing means sets the standby position after the detection at a distance in the case of a sheet having a large size in the transport direction, and sets the standby position after the detection in a case of a sheet having a small size in the transport direction. It is characterized by being placed near.

The present invention sequentially detects a reference position in a direction perpendicular to the sheet conveying direction, a standby position determined according to the width of the sheet, a detection position for detecting the sheet edge, and the standby position. The present invention relates to a sheet misalignment detection device that detects misalignment in the sheet width direction during conveyance using a sheet edge detection unit that performs an operation.

In order to achieve the above object, the present invention has a standby position changing means for changing a standby position of the sheet end detecting means in accordance with a size of a detected sheet in a conveying direction. .

The standby position changing means sets the distance from the reference position to the standby position small for a sheet having a large size in the conveying direction, and sets the reference distance for a sheet having a small size in the conveying direction. The distance from the position to the standby position is set to be large.

[0017]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an overall configuration of a digital copying apparatus (image forming apparatus, sheet processing apparatus) provided with a sheet position deviation detecting apparatus according to the present invention.

First, the overall configuration of the digital copying apparatus will be described.

Reference numeral 1 denotes a document feeder, which feeds a document (not shown) placed on a predetermined portion to a predetermined position on the platen glass surface 2 one by one or continuously.

Reference numeral 3 denotes a scanner comprising a document illumination lamp 4, a scanning mirror 5, and the like. When a document is placed on the document table glass surface 2 by the document feeder 1, the scanner is reciprocally scanned in a predetermined direction. The original reflected light is scanned by scanning mirrors 5-7 and lens 8.
The image is formed on the image sensor unit 101 via.

Reference numeral 10 denotes an exposure control unit constituted by a laser scanner, which applies a light beam modulated based on image data output from an image signal control unit (not shown) of the controller unit 9 to a photosensitive member (photosensitive drum). Irradiate 11.

Developing devices 12 and 13 visualize the electrostatic latent image formed on the photoreceptor 11 with a developer (toner) of a predetermined color.

Reference numerals 14 and 15 denote sheet stacking units (cassettes) in which sheets S of a fixed size are stacked and stored, and are fed to the registration roller pair 25 by driving the feed rollers 14a and 15a. Photoconductor 1
The sheet is conveyed at a timing when the position of the toner formed on the sheet No. 1 and the front end of the sheet are adjusted.

Reference numeral 16 denotes a transfer separation charger, which is a photosensitive member 11
After the developed toner image is transferred, the sheet S is separated from the photoconductor 11. The separated sheet S is transport belt 2
5, the toner image is sent to the fixing roller pair 17 and fixed.

Reference numeral 18 denotes a paper discharge roller pair, which discharges the sheet S on which an image has been formed onto a paper discharge tray (not shown) outside the apparatus.

Reference numeral 20 denotes a direction flapper, which switches the conveying direction of the sheet S on which the image formation has been completed between the sheet discharge port side and the re-feed path side.

The image signal input to the image sensor unit 101 is processed by an image signal control unit (not shown) in the controller unit 9 and then reaches a printer control unit (not shown).

The signal input to the printer control unit is converted into an optical signal by the exposure control unit 10 and irradiates the photoconductor 11 in accordance with the image signal.

The latent image formed on the photosensitive member 11 by the irradiation light is developed by the developing device 12 or the developing device 13.

In the duplex mode, after the trailing edge of the sheet S has passed the paper discharge sensor 19, the paper discharge roller pair 18 is rotated in the direction opposite to the paper discharge direction. At the same time, Flapper 2
0 is switched to the re-feeding path side, and the sheet S on which the first surface image has been formed is stored in the intermediate tray 24 via the conveyance paths 22 and 23.

In the multiplex mode, the flapper 21 is switched to the re-feeding path side, and the previously formed sheet S is stored in the intermediate tray 24 via the conveying paths 22 and 23.

The number of sheets S stored in the intermediate tray 24 is 1
The sheets are fed to the image forming unit one by one.

Next, a method of stacking the sheets S on the intermediate tray 24 will be described with reference to FIGS.

The sheet S that has passed through the fixing roller pair 17 is
The sheet is conveyed to the conveying roller pair 27 by the sheet discharging roller 18 or 26. In order to pull out the trailing end of the sheet S nipped by the pair of conveying rollers 27 from the pair of conveying rollers 27, the pair of conveying rollers 28 is rotated by a predetermined distance LO after the front end of the sheet is nipped by the pair of conveying rollers 28 ( (Fig. 3). Subsequently, the conveying roller pair 2 is moved so that the leading end of the sheet is positioned at a predetermined distance L from the nip of the conveying roller pair 28.
8 is reversely rotated. As a result, the trailing edge of the sheet enters the retreat area 24A below the pair of conveying rollers 27 (see FIG.
4) . Here, it is determined whether or not the stacking of the set number of sheets has been completed. If the stacking has not reached the set number of sheets, for example, the second sheet S2 is conveyed. Performs the same operation as the previous one while holding the first sheet S1, and overlaps the front end of the second sheet S2 by a distance L from the front end of the first sheet S1. By repeating this operation for the second and subsequent sheets, as shown in FIG. 5, the sheets S3, S4.

Next, a method of re-feeding the sheets S stacked on the intermediate tray 24 for forming the next image will be described with reference to FIGS.

A plurality of sheets S held between the pair of conveying rollers 28 are conveyed to the separation flapper 30 by a pair of conveying rollers 29 synchronized with the pair of conveying rollers 28 at a predetermined interval. When the leading end of the lowermost sheet S1 has passed the distance M from the nip of the pair of conveying rollers 29, the conveying roller pairs 28 and 29 are stopped, and the separation flapper 30 at the position shown by the dotted line is lowered to the position shown by the solid line ( Figure
6) . At this time, the leading end of the lowermost sheet S1 and the leading end of the next sheet S2 are separated by a distance L.
The leading end of 0 will abut between the lowest sheet S1 and the next sheet S2. Subsequently, the transport roller pairs 28 and 29 and the re-feed roller pair 31 are rotated until the rear end of the lowermost sheet S1 is pulled out of the nip of the transport roller pair 29. At this time, the second and subsequent sheets S2, S3, S4
Are stocked in the upper area of the flapper 30, and the lowermost sheet S1 is separated (FIG. 7). When the trailing edge of the lowermost sheet S1 is pulled out of the nip of the pair of transport rollers 29, the pair of transport rollers 28 and 29 is positioned upstream of the distal end of the separation flapper 30 where the leading edge of the sheet S2 is at the position shown by the solid line. Reverse rotation until Subsequently, the separation flapper 30 is raised to the position shown by the dotted line in FIG. The separation flapper 30 repeatedly descends and rises each time the sheet S is conveyed to the re-feed roller pair 31. Subsequently, one of the separated lowermost sheets S <b> 1 is fed by the re-feed roller 31.

The sheet S fed by the re-feed roller 31 is conveyed to the registration roller pair 25 by the conveyance roller pairs 32 and 34, and at the upstream portion of the conveyance roller pair 32, the sheet displacement detecting apparatus of the present invention is used. 33 (see FIG. 2), a positional deviation (lateral deviation) in the sheet width direction is detected.

That is, in the sheet displacement detecting device 33 of the present invention, as shown in FIG. 8, the sheet S to be moved along the transport center moves with a displacement in the width direction. State), the positional deviation amount (lateral deviation amount) in the width direction is detected.

Hereinafter, the sheet displacement detecting device 3 of the present invention will be described.
Reference numeral 3 denotes a sheet end detection unit (referred to as a detection sensor) 33a movable in a direction orthogonal to the sheet conveyance direction, and a sensor driving unit 33c for driving the detection sensor 33a in a direction orthogonal to the sheet conveyance direction. And a CPU 33b for controlling the sensor driving means 33c.
The CPU 33b is control means for controlling the operation of the entire image forming apparatus.

Next, a detection operation performed by the detection sensor 33a will be described with reference to FIGS. In addition,
FIG. 9 is a cross-sectional view showing the order of the detection operation, and the sheet S moves in a direction perpendicular to the plane of the drawing. 10 to 14 are plan views showing the sequence of the detection operation, and the sheet S moves rightward on the paper.

When the sheets S are stacked on the intermediate tray 24, the detection sensor 33a is located at the reference position P1 (FIG. 9A). Then, when a predetermined time has elapsed since the sheet S stacked on the intermediate tray 24 starts being re-fed by the re-feed roller pair 31, the detection sensor 33a located at the reference position P1 detects the sheet S in accordance with the sheet width size. Move to a predetermined waiting position P2 before detection (FIG. 9
(b), FIG. 10).

Note that sheets S of various widths and lengths (sizes in the transport direction) are stacked on the intermediate tray 24. Here, even sheets having the same width and smaller than a certain length are stacked. A short sheet Sa is called , and a sheet longer than a certain length is called a long sheet Sb. Then, a case will be described in which the misalignment between the short sheet Sa and the long sheet Sb re-fed from the intermediate tray 24 is detected.

Next, when a predetermined time elapses after the sheet S stacked on the intermediate tray 24 starts being re-fed by the re-feed roller pair 31, the standby position P before detection is reached.
The detection sensor 33a located at 2 moves to the position P3 for detecting the sheet edge. In this case, the detection sensor 33a can move to a position P4 at which the sheet end can be reliably detected, and detects the sheet end at a position P3 on the way to the position P4 (FIGS. 9C and 11). ).

The detection sensor 33a that has detected the sheet edge at the position P3 moves to the standby position P5 after the detection, and prepares for the detection of the positional deviation of the next sheet S (FIGS. 9 (d) and 9 (e), FIG. 1).
2, FIG. 14).

In the present invention, the position of the standby position P5 after the detection is changed between the short sheet Sa and the long sheet Sb even if the sheets have the same width size. In the case of the short sheet Sa,
Standby position P5 after detection at distance H4 close to detection position P3
(FIGS. 9D and 12). Further, in the case of the long sheet Sb, a short distance H4 + Δx from the detection position P3.
The standby position after the detection is placed at (Fig. 9 (e), Fig. 1).
4). Next, the reason will be described.

As shown in FIG. 12, in the case of the short sheet Sa, even if the standby position P5 after the detection is set at a distance H4 close to the detection position P3, the skewed short sheet Sa remains at the standby position P5 after the detection. Does not interfere with the detection sensor 33a. However, as shown in FIG.
In this case, if the standby position P5 after the detection is placed at the same distance H4 as the short sheet Sa, the obliquely long sheet Sb interferes with the detection sensor 33a at the standby position P5 after the detection, and Torn or jammed.

For this reason, in the case of the long sheet Sb, as shown in FIG. 14, the standby position P5 after the detection is located at a distance H4 + Δx far from the detection position P3, and the obliquely long sheet Sb is skewed. The sheet Sb does not interfere with the detection sensor 33a at the standby position P5 after the detection.

The distance H to the standby position P5 after the detection is obtained.
4, H4 + Δx is set to the minimum distance in which the skewed short sheet Sa and long sheet Sb do not interfere with the detection sensor 33a, so that the displacement detection of the next sheet can be quickly performed.

Next, with reference to FIG. 15, a description will be given of a control procedure for detecting a positional deviation performed by the CPU 33b.

First, the width and length (short or long) of the sheet S re-fed from the intermediate tray 24 are detected (S1). Next, the reference position P
1 is set to a value H1 corresponding to the detected width size from the distance from the standby position P2 before detection to the width size where the distance from the standby position P2 before detection to the position P4 where the detection sensor 33b can move is detected. The value is set to H2 according to the detection position P
The distance from 3 to the standby position P5 after detection is set to a value H4 or H4 + Δx (H4 for a short size, H4 + Δx for a long size) according to the detected length size (S2). Next, the re-feed roller pair 31 starts the re-feed operation (S3), and after a lapse of a predetermined time (S4), the detection sensor 33a moves from the reference position P1 to the standby position P2 before detection.
(S5). Subsequently, after a lapse of a predetermined time (S6), the detection sensor 33a is moved from the standby position P2 before detection to a movable position P4 (S7).

Next, it is checked whether or not the detection sensor 33a has detected the sheet edge (S8), and if it is detected, the position from the reference position P1 to the sheet edge is calculated (S8).
9) Subsequently, the standby position P after detecting the detection sensor 33a
5 (S10), and the sequence ends.

If the detection sensor 33a does not detect the sheet edge in S8, it is checked whether the detection sensor 33a has moved to a movable position P4 (S1).
1) If it has not moved to the position P4, the process returns to S8, and if it has moved to the position P4, it is determined that an abnormality such as a sheet conveyance failure has occurred, and abnormality processing is performed (S12).
This sequence ends.

The sheet displacement detecting apparatus of the present invention detects not only the displacement of the sheet immediately after being fed from the sheet stacking means (such as the intermediate tray 24) but also the displacement of the sheet being conveyed. Can also.

The detection sensor 33a moves in the order of the reference position P1, the standby position P2 before the detection, the detection position P3, the standby position P5 after the detection, and the standby position P2 before the detection and the standby position P5 after the detection. Is a different position, but the standby position P2 before detection and the standby position P5 after detection may be the same position. In this case, the standby position is changed according to the sheet length size (short size or long size). That is, in the case of a short-sized sheet Sa,
The distance from the reference position to the standby position is set large, and in the case of a long sheet Sb, the distance from the reference position to the standby position is set small.

[0056]

As described above, in the sheet displacement detecting apparatus of the present invention, the sheet is conveyed to the standby position after the detection by the sheet end detecting means (or the standby position before and after the detection is the same). Since the length of the sheet is changed depending on the direction size, the skewed long sheet does not interfere with the sheet edge detection unit that is waiting after the detection. Also,
Particularly, in the case of a short sheet, the sheet end detecting means moves from the standby position close to the detection position to the detection position, so that the detection can be performed quickly.

[Brief description of the drawings]

FIG. 1 is a vertical cross-sectional side view showing an overall configuration of a digital copying apparatus provided with a sheet displacement detecting device of the present invention.

FIG. 2 is a side view showing a circulation path of double-sided copying and multiple copying sheets in the copying apparatus.

FIG. 3 is a vertical cross-sectional side view illustrating a process in which double-sided copying and multiple copying sheets are stacked on an intermediate tray of the copying apparatus.

FIG. 4 is a vertical sectional side view for explaining a process in which double-sided copying and multiple copying sheets are stacked on an intermediate tray of the copying apparatus.

FIG. 5 is a vertical sectional side view for explaining a process in which double-sided copying and multiple copying sheets are stacked on an intermediate tray of the copying apparatus.

FIG. 6 is a longitudinal sectional side view for explaining a method of separating sheets stacked on an intermediate tray one by one from the lowest sheet.

FIG. 7 is a vertical sectional side view illustrating a method of separating sheets stacked on an intermediate tray one by one from the lowest sheet.

FIG. 8 is a plan view for explaining a position shift of a sheet to be subjected to position shift detection by the sheet position shift detection device of the present invention.

FIG. 9 is a cross-sectional view illustrating an operation of a detection sensor in the sheet displacement detection device of the present invention.

FIG. 10 is a plan view for explaining the operation of a detection sensor in the sheet position deviation detecting device of the present invention.

FIG. 11 is a plan view for explaining the operation of a detection sensor in the sheet displacement detection device of the present invention.

FIG. 12 is a plan view for explaining the operation of a detection sensor in the sheet displacement detection device of the present invention.

FIG. 13 is a plan view for explaining a problem in detecting a displacement of a long sheet.

FIG. 14 is a plan view for explaining the operation of a detection sensor in the sheet position deviation detecting device of the present invention.

FIG. 15 is a flowchart illustrating a control procedure of position shift detection performed by the CPU.

[Explanation of symbols]

 Reference Signs List 11 photoconductor (image forming unit, sheet processing unit) 24 intermediate tray (sheet stacking unit) 33 sheet position deviation detecting device 33a detection sensor (sheet end detecting unit) 33b CPU (standby position changing unit) P1 reference position P2 before detection Standby position P3 Detection position P5 Standby position after detection Sa Short sheet Sb Long sheet

Continuation of the front page (56) References JP-A-6-144647 (JP, A) JP-A-62-16959 (JP, A) JP-A-5-11530 (JP, A) JP-A-2-56386 (JP) , A) (58) Field surveyed (Int. Cl. ⁷ , DB name) B65H 7/06 B65H 7/10

Claims (9)

(57) [Claims] 1. A detection position is sequentially detected from a reference position in a direction orthogonal to a sheet conveying direction to a standby position determined according to a sheet width size, a detection position for detecting a sheet edge, and a standby position after detection. In a sheet misalignment detection device that detects a misalignment in the width direction of a sheet being conveyed using a sheet edge detection unit that performs an operation, a sheet conveyance direction size in which a standby position after detection by the sheet end detection unit is detected And a standby position changing unit for changing the position of the sheet in accordance with the standby position. 2. A detecting operation is sequentially performed from a reference position in a direction orthogonal to a sheet conveying direction to a standby position determined according to a sheet width size, a detection position for detecting a sheet edge, and the standby position. In a sheet displacement detection device that detects a displacement in the width direction of a sheet being conveyed by using a sheet end detection unit that performs the operation, the standby position of the sheet end detection unit is changed according to the size of the detected sheet in the conveyance direction. A sheet position deviation detecting device comprising a standby position changing unit. 3. The standby position changing means places the standby position after the detection at a distance in the case of a sheet having a large transport direction size, and sets the standby position after the detection in a case of a sheet having a small transport direction size. The sheet position deviation detecting device according to claim 1, wherein the sheet position deviation detecting device is placed near. 4. The standby position changing means sets a small distance from the reference position to the standby position for a sheet having a large transport direction size, and sets the reference position for a sheet having a small transport direction size. 3. The sheet position deviation detecting device according to claim 2, wherein the distance from the position to the standby position is set large. 5. The sheet position deviation detecting device according to claim 1, wherein the sheet end detecting unit detects a position deviation in a width direction of the sheets fed one by one from the sheet stacking unit. 6. The sheet position deviation detecting device according to claim 5, wherein a plurality of sheets re-fed to the image forming unit are stacked on the sheet stacking unit. 7. The sheet stacking means according to claim 5, wherein a plurality of sheets are stacked on the sheet stacking means with their leading ends shifted by a predetermined amount, and are sequentially fed out from the earliest sheet. Sheet position deviation detection device. 8. An image forming unit for forming an image on a sheet fed one by one, and a sheet stacking unit for temporarily stacking a sheet on which an image has been formed by the image forming unit for image formation again An image forming apparatus comprising: a sheet position deviation detecting device according to any one of claims 5 to 7. 9. A sheet processing means for performing a predetermined process on sheets fed one by one, and the sheet position deviation detecting device according to any one of claims 1 to 4. A sheet processing apparatus, characterized in that: